Indo-French TRISHNA thermal imaging satellite expected to launch in 12 to 16 months
A satellite that measures how hot the ground is could tell farmers how thirsty their crops are. When will it fly?
Published 12 October 2026. Written by Pratidin from the reports linked at the end; every fact checked by a separate review before publishing. How we work
TRISHNA (Thermal infraRed Imaging Satellite for High-resolution Natural resource Assessment), a joint Earth observation mission of the Indian Space Research Organisation (ISRO) and France's space agency CNES, is expected to be launched in 12 to 16 months, The Hindu reported on 12 October 2026. The report says the mission, planned over about a decade, is now in its realisation stage, with ISRO building the satellite platform. It will be the third Indo-French satellite after Megha-Tropiques, launched on 12 October 2011, and SARAL, launched on 25 February 2013. CNES lists the launch as scheduled for 2027, with a five-year mission life.
The satellite carries two instruments. CNES is developing the thermal infrared (TIR) instrument, whose development by Airbus began on 4 June 2020, and ISRO supplies an optical sensor that observes the visible and shortwave infrared alongside it. According to CNES, TRISHNA will fly in a sun-synchronous orbit at 761 km, crossing the equator at 12:30 local time, with a field of view of plus or minus 34 degrees. Its camera resolution is 57 to 90 m, with products at 60 m, and it will revisit the same point at the equator every three days. That combination of fine resolution and frequent revisit in the thermal band is what sets it apart from most existing missions, which offer one or the other.
The main aim is to measure land surface temperature, which reveals how much water plants are losing through evapotranspiration, the combined loss of water from soil evaporation and plant transpiration. Stressed, thirsty crops are warmer than well-watered ones. This makes TRISHNA useful for tracking water stress, irrigation efficiency and drought, a priority for a country where agriculture is the largest user of water. Secondary uses include monitoring urban heat islands, coastal waters, snowmelt and glaciers, and detecting thermal anomalies. The mission continues more than six decades of India-France space ties, which began with a 1964 protocol on space research.
Prelims facts
- TRISHNA stands for Thermal infraRed Imaging Satellite for High-resolution Natural resource Assessment, a joint ISRO-CNES mission.
- The Hindu reported on 12 October 2026 that it is expected to launch in 12 to 16 months; CNES lists the launch for 2027 with a five-year life.
- CNES builds the thermal infrared instrument and ISRO the optical sensor; resolution is 57 to 90 m with 60 m products and a three-day revisit at the equator.
- It will fly in a sun-synchronous orbit at 761 km and mainly measure land surface temperature to track evapotranspiration and water stress.
- It is the third Indo-French satellite after Megha-Tropiques (2011) and SARAL (2013).
Quick recall
- Expand TRISHNA.
- Thermal infraRed Imaging Satellite for High-resolution Natural resource Assessment.
- Which agencies are building TRISHNA?
- ISRO and CNES (France).
- Who builds TRISHNA's thermal infrared instrument?
- CNES (with development by Airbus); ISRO supplies the optical sensor.
- In what orbit will TRISHNA fly?
- Sun-synchronous orbit at 761 km, crossing the equator at 12:30 local time.
- TRISHNA's resolution and revisit?
- 57 to 90 m camera resolution, 60 m products; revisit every three days at the equator.
- What is evapotranspiration?
- Combined water loss from soil evaporation and plant transpiration.
- When and on which rocket was Megha-Tropiques launched?
- 12 October 2011, on PSLV-C18.
- What does SARAL stand for, and when was it launched?
- Satellite with ARgos and ALtika; 25 February 2013, on PSLV-C20.
Prelims practice question
With reference to the TRISHNA mission, consider the following statements:
1. It is a joint mission of ISRO and the French space agency CNES.
2. Its primary purpose is to measure land surface temperature to assess water stress and evapotranspiration.
3. It will be placed in a geostationary orbit to provide continuous coverage of India.
Which of the statements given above are correct?
- 1 and 2 only
- 2 and 3 only
- 1 and 3 only
- 1, 2 and 3
Show answer
Answer: (a) 1 and 2 only. Statements 1 and 2 are correct. Statement 3 is incorrect: TRISHNA will fly in a sun-synchronous orbit at about 761 km, revisiting each point at the equator every three days, not in geostationary orbit at about 36,000 km.
Use this in UPSC Mains: previous-year questions
Recurring theme: Space technology for socio-economic development and natural resource management.
- How to use this
Cite TRISHNA to show how Indian space capability, built with partners, is turning to farm water management and climate monitoring.
- TRISHNA, a joint ISRO-CNES satellite due for launch in 2027, will map land surface temperature to estimate crop water stress.
- It offers 60 m products with a three-day revisit at the equator, enabling field-scale irrigation and drought monitoring.
- It follows Megha-Tropiques (2011) and SARAL (2013), showing sustained Indo-French space cooperation.
What is water stress? How and why does it differ regionally in India?
How to use thisEnd by noting that satellite thermal data will let India map water stress regionally and at field scale, improving targeted responses.
- TRISHNA's thermal sensor will estimate evapotranspiration, the water crops actually consume, revealing stress before visible wilting.
- Its three-day revisit at the equator and 57 to 90 m resolution allow field-scale tracking of water stress and drought.
Mains practice question
How can satellite-based thermal infrared observation help India manage water use in agriculture? Discuss with reference to the Indo-French TRISHNA mission. (150 words)
Model answer
Agriculture is India's largest user of water, yet farm-level water use is rarely measured. TRISHNA, a joint ISRO-CNES mission expected to launch in 12 to 16 months, aims to fill that gap from space.
How thermal observation helps
- Crop water stress: Thirsty plants transpire less and heat up; land surface temperature reveals stress before crops visibly wilt.
- Evapotranspiration estimates: Combining thermal and optical data gives water actually consumed by fields, useful for irrigation scheduling.
- Irrigation efficiency: Comparing command areas helps target canal releases and groundwater regulation.
- Drought monitoring: Frequent revisits, every three days at the equator, allow early warning.
Why TRISHNA is different
- 57 to 90 m resolution with 60 m products, fine enough for field-scale analysis.
- CNES provides the thermal instrument and ISRO the optical sensor and the satellite platform.
Limits
- Data must reach farmers through State agencies and advisories; cloud cover limits thermal imaging.
If integrated with irrigation planning, TRISHNA could help India grow more crop per drop.
The basics
Why this matters
Every hot afternoon, fields lose water to the air. How much they lose tells us whether crops are healthy or stressed, and whether irrigation water is being used well. Ground sensors can measure this at a few points; a satellite can measure it across a country. TRISHNA, a joint mission of ISRO and the French space agency CNES, is built to do exactly that.
Seeing heat from space
All objects give off thermal infrared radiation, and warmer surfaces give off more. A thermal sensor can therefore map land surface temperature. Because a well-watered plant cools itself by releasing water vapour through its leaves, a stressed plant is warmer than a healthy one. See Thermal infrared remote sensing and Evapotranspiration and water stress.
- 1MeasureThe thermal instrument records radiation from the surface.
- 2ConvertScientists derive land surface temperature and emissivity.
- 3CombineOptical data on vegetation are added to estimate evapotranspiration.
- 4Map stressFields losing less water than expected show up as stressed.
- 5ActAgencies adjust irrigation, issue advisories or track drought.
What the satellite carries
- 1Thermal infrared instrumentBuilt by CNES (developed by Airbus); measures surface temperature.
- 2Optical sensorSupplied by ISRO; observes visible and shortwave infrared alongside the thermal instrument.
- 3Satellite platformBuilt by ISRO.
- 4OrbitSun-synchronous at 761 km, crossing the equator at 12:30 local time.
The orbit matters. A Sun-synchronous orbit lets the satellite pass over each place at the same local time, so temperature readings taken on different days can be compared fairly.
Resolution and revisit
Most thermal missions force a trade-off: either sharp images taken rarely, or frequent images that are coarse. TRISHNA aims to break it, with 57 to 90 m camera resolution, 60 m products and a revisit every three days at the equator.
A long partnership
TRISHNA is the third Indo-French satellite, after Megha-Tropiques and SARAL. The partnership dates to a 1964 protocol on space research; see India-France space cooperation.
- 1964India and France sign a protocol on space research cooperation
- 12 Oct 2011Megha-Tropiques launched on PSLV-C18 to study the tropical water cycle
- 25 Feb 2013SARAL launched on PSLV-C20 with the AltiKa altimeter
- 4 Jun 2020Development of TRISHNA's thermal instrument begins
- 2027TRISHNA launch scheduled, per CNES
Go deeper
In one line: TRISHNA, a joint ISRO-CNES satellite that will map land surface temperature at fine resolution every few days, is expected to launch in 12 to 16 months.
Why it matters for UPSC
Prelims regularly asks about named satellites, partner agencies and orbits. Mains links space technology to agriculture, water management and climate, and to India's strategic partnerships such as the one with France.
The core idea
TRISHNA uses Thermal infrared remote sensing to measure how hot the land is. That temperature reveals Evapotranspiration and water stress: how much water fields are losing and whether crops are stressed. Its Sun-synchronous orbit makes readings on different days comparable. The mission is the latest chapter in India-France space cooperation.
Numbers and dates to remember
- 12 to 16 months to launch (The Hindu, 12 October 2026); CNES lists 2027.
- 761 km sun-synchronous orbit; 12:30 equator crossing.
- 57 to 90 m resolution, 60 m products; three-day revisit at the equator.
- Five-year mission life.
- Megha-Tropiques: 12 October 2011, PSLV-C18. SARAL: 25 February 2013, PSLV-C20.
Where to go next
- Thermal infrared remote sensing: how a satellite reads temperature.
- Evapotranspiration and water stress: why heat tells us about water.
- Sun-synchronous orbit: why the orbit choice matters.
- India-France space cooperation: six decades of partnership.
Go deeper: what TRISHNA adds, and what it cannot do
The gap it fills. Existing thermal sensors tend to offer either fine detail with infrequent passes or frequent passes with coarse pixels. For agriculture, both are needed: fields are small, and water stress can build within days. TRISHNA's design, 60 m products with a three-day revisit at the equator, aims to meet both needs. Using Thermal infrared remote sensing together with optical data allows scientists to estimate Evapotranspiration and water stress field by field.
Uses for India. Irrigation departments could compare how efficiently canal commands use water. Drought monitoring could move from rainfall deficits to actual crop stress. Cities could map urban heat islands to plan cooling measures. Glaciologists could follow snowmelt in the Himalaya.
Limits. Thermal sensors cannot see through cloud, which limits monsoon-season coverage. Converting raw data into useful advice needs ground calibration, trained State agencies and data-sharing rules. A sun-synchronous orbit, explained in Sun-synchronous orbit, fixes the time of observation, which aids comparison but also means the satellite sees each place only around the same time of day.
The partnership angle. India-France space cooperation has moved from France supplying sounding rockets in the 1960s to joint missions in which India builds the satellite. TRISHNA's division of work, CNES's thermal instrument on an ISRO-built satellite, reflects a more equal partnership.
Thermal infrared remote sensing
How a satellite reads the temperature of the ground.
In one line: Thermal infrared remote sensing measures the heat radiation given off by surfaces to estimate their temperature.
The basic idea
Every object above absolute zero emits electromagnetic radiation, and warmer objects emit more. In the thermal infrared part of the spectrum, this emitted radiation can be measured by a sensor on a satellite. After correcting for the atmosphere and for emissivity, which is how efficiently a surface emits compared with an ideal emitter, scientists derive land surface temperature.
Thermal versus optical
Optical sensors measure sunlight reflected by surfaces and so work only in daylight. Thermal sensors measure emitted heat and can work by day or night, but like optical sensors they cannot see through cloud.
Why it is in the news
TRISHNA's main instrument, built by CNES, is a thermal infrared imager designed to give fine resolution with frequent revisits.
Where to go next
Evapotranspiration and water stress
Why heat tells us how thirsty crops are.
In one line: Evapotranspiration is the total water lost to the air from soil evaporation and plant transpiration; a shortfall signals water stress.
How it works
Plants draw water from the soil and release it through tiny pores in their leaves. This transpiration cools the leaves, much as sweat cools skin. When soil water runs short, plants close these pores to save water, transpiration falls and leaves heat up.
Why it matters
Measuring evapotranspiration tells water managers how much water crops actually consume, which is different from how much was supplied. It helps schedule irrigation, compare the efficiency of canal systems and detect drought early.
The TRISHNA link
By combining land surface temperature from the thermal sensor with optical data on vegetation, TRISHNA aims to estimate evapotranspiration and terrestrial water stress at field scale.
Where to go next
Sun-synchronous orbit
Why the choice of orbit makes temperature readings comparable.
In one line: A sun-synchronous orbit is a near-polar orbit in which a satellite passes over any given latitude at the same local solar time on every pass.
How it works
The orbit's plane slowly rotates, at the same rate that the Earth moves around the Sun, so the angle between the orbit and the Sun stays constant. Most Earth observation satellites use such orbits at a few hundred kilometres above the surface.
Why it matters for TRISHNA
Surface temperature changes through the day. If a satellite observed a field at 10 a.m. one day and 3 p.m. the next, the readings would not be comparable. TRISHNA's orbit at 761 km, crossing the equator at 12:30 local time, ensures consistent timing.
Contrast
A geostationary satellite, at about 36,000 km above the equator, stays over one spot and suits weather and communication, but is too far for fine-resolution thermal mapping.
Where to go next
India-France space cooperation
Six decades of partnership, from sounding rockets to joint satellites.
In one line: India and France have cooperated in space since a 1964 protocol, and have built joint satellites since 2011.
Milestones
- 1964: India and France agree a programme of cooperation in space research; France later supplies Centaure sounding rockets.
- 1981: India's first communication satellite, APPLE, is launched on a French Ariane-1 rocket.
- 12 October 2011: Megha-Tropiques, on PSLV-C18, to study the water cycle and energy exchanges in the tropical atmosphere.
- 25 February 2013: SARAL, on PSLV-C20, carrying the French ARGOS and AltiKa payloads; AltiKa measures sea surface height.
- 2015: joint stamps mark 50 years of cooperation.
Why it is in the news
TRISHNA will be the third Indo-French satellite. Its division of work, a CNES instrument on an ISRO satellite, shows how the partnership has become more balanced.
Where to go next
Take the 12 October 2026 quiz: 30 Prelims-style questions with answers